SELinux: Socket retains creator role and MLS attribute

The socket SID would be computed on creation and no longer inherit
its creator's SID by default. Socket may have a different type but
needs to retain the creator's role and MLS attribute in order not
to break labeled networking and network access control.

The kernel value for a class would be used to determine if the class
if one of socket classes. If security_compute_sid is called from
userspace the policy value for a class would be mapped to the relevant
kernel value first.

Signed-off-by: Harry Ciao <qingtao.cao@windriver.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>

1 files changed, 24 insertions, 4 deletions

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 2e36e03c21f2..3e7544d2a07b 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -201,6 +201,21 @@ static u16 unmap_class(u16 tclass)
         return tclass;
 }
 
+/*
+ * Get kernel value for class from its policy value
+ */
+static u16 map_class(u16 pol_value)
+{
+        u16 i;
+
+        for (i = 1; i < current_mapping_size; i++) {
+                if (current_mapping[i].value == pol_value)
+                        return i;
+        }
+
+        return pol_value;
+}
+
 static void map_decision(u16 tclass, struct av_decision *avd,
                          int allow_unknown)
 {
@@ -1374,6 +1389,7 @@ static int security_compute_sid(u32 ssid,
         struct avtab_node *node;
         u16 tclass;
         int rc = 0;
+        bool sock;
 
         if (!ss_initialized) {
                 switch (orig_tclass) {
@@ -1391,10 +1407,13 @@ static int security_compute_sid(u32 ssid,
 
         read_lock(&policy_rwlock);
 
-        if (kern)
+        if (kern) {
                 tclass = unmap_class(orig_tclass);
-        else
+                sock = security_is_socket_class(orig_tclass);
+        } else {
                 tclass = orig_tclass;
+                sock = security_is_socket_class(map_class(tclass));
+        }
 
         scontext = sidtab_search(&sidtab, ssid);
         if (!scontext) {
@@ -1425,7 +1444,7 @@ static int security_compute_sid(u32 ssid,
         }
 
         /* Set the role and type to default values. */
-        if (tclass == policydb.process_class) {
+        if ((tclass == policydb.process_class) || (sock == true)) {
                 /* Use the current role and type of process. */
                 newcontext.role = scontext->role;
                 newcontext.type = scontext->type;
@@ -1482,7 +1501,8 @@ static int security_compute_sid(u32 ssid,
 
         /* Set the MLS attributes.
            This is done last because it may allocate memory. */
-        rc = mls_compute_sid(scontext, tcontext, tclass, specified, &newcontext);
+        rc = mls_compute_sid(scontext, tcontext, tclass, specified,
+                             &newcontext, sock);
         if (rc)
                 goto out_unlock;